The present invention is directed to a conveyor belt system for a continuous mining machine and more specifically to an extendable and retractable conveyor belt system connected between the continuous mining machine and a conveyor belt drive and belt storage device located externally of a mine shaft in which the continuous mining machine is operating.
In many parts of the country, particularly in the coal strip mines east of the Mississippi River, thousands of miles of out-cropped coal have been mined leaving many seams of coal exposed which generally have a low seam height precluding the economical recovery of the coal by strip or conventional deep mining techniques. Many of these low-height coal seams have been mined by horizontally disposed augers, but such augers are generally only suitable for penetration of a few hundred feet into the coal seam. Thus, a vast percentage of the coal is left untouched. Since the height of these coal seams is so low, it is extremely difficult, if not impossible, to mine the coal with people in the shaft.
The use of continuous mining machines is generally old and well known in the art which utilize conveyor systems which may be extended and retracted. The patent to Baechli, U.S. Pat. No. 3,289,816, discloses a continuous mining machine in combination with an extendable conveyor where the conveyor belt storage means is located within a crawler mounted housing which is moveable in the tunnel behind the continuous mining machine. Baechli utilizes two tensioned ropes for supporting the conveyor belt. The patent to Thompson, U.S. Pat. No. 4,312,540, also discloses a continuous mining apparatus which includes an extendable conveyor system. In this patent the conveyor system is telescopic in nature and is adapted to be mounted directly within the mine shaft.
One of the principal problems with extendable and retractable conveyor belt systems involves the supporting and tensioning of the conveyor belt so that it can properly convey the coal form the continuous mining machine to a point remote from the mine face. While it is known in the art to provide a plurality of spaced support stands for the conveyor which are interconnected by various types of cables, there is no effective tensioning system which also acts as a retrieval system for the conveyor belt supports nd the mining machine. Examples of the various conveyor belt support systems are disclosed in the U.S. patents to Poundstone, U.S. Pat. No. 3,039,596; Delli-gati, U.S. Pat. No. 4,120,535; Long, U.S. Pat. No. 3,146,878; Long, U.S. Pat. No. 3,268,060; and Thompson, U.S. Pat. No. 2,796,167.